docs: def orbit_y(self, angle):
          '''Orbit around the point ``Camera.pivot`` by the angle
          *angle* expressed in radians. The axis of rotation is the
          camera "right" vector, ``Camera.a``.
  
          In practice, we move around a point like if we were on a Ferris
          wheel.
  
          '''
          
          # Subtract pivot point
          self.position -= self.pivot
          
          # Rotate
          rot = rotation_matrix(-angle, self.b)[:3,:3]
          self.position = np.dot(rot, self.position)
          
          # Add again the pivot point
          self.position += self.pivot
          
          self.a = np.dot(rot, self.a)
          self.b = np.dot(rot, self.b)
          self.c = np.dot(rot, self.c)